Changing a river into a lake is basically what a large dam does. one reason we do this to create reservoirs of fresh water. however, dams change the local ecosystem in a big way. what is one negative impact of building a dam

One negative impact of building a dam could be that it affects natural habitats of animals who live in and around the river. When you build a dam, the river's height becomes smaller because a huge amount of water becomes technically removed or blocked. This can affect animals such as fish or beavers or anyone who needs that water.

Carbon-14 has a half-life of 5,730 years and most igneous rock is older than that.